1. Field of the Invention
The present invention concerns the spatial domain and, more particularly, a satellite adapted in flight to control objects floating in space using electromagnetic forces and electromagnetic torques.
2. Description of the Prior Art
Satellites flying in formation to detect extrasolar planets are known in the art. These formation flights necessitate a plurality of satellites (typically six satellites) with extremely tight relative positioning requirements. Other types of constellations are envisaged in the astronomy field, for synthetic aperture imaging by simulating a mirror whose maximum dimensions correspond to the maximum distance between two satellites (typically of the order of several hundred meters). These dimensions are obviously not compatible with the diameters available under the nose-cap of current launch vehicles (typically a few meters) and therefore make a major technological leap. The orbit for this type of application is generally chosen from the Lagrange points (typically L2) for the extremely stable character of the conditions (thermal, gravitational, radiation) that reign therein, allowing the installation of very sensitive and cooled payloads. In terms of formation flying performance, this implies micrometric or even nanometric accuracy and stability over relatively long periods of time (possibly up to a few days).
To satisfy these requirements, the constellation must comprise a certain number of satellites, very accurate metrology subsystems and extremely accurate and very low noise propulsion subsystems.
The concepts classically adopted to satisfy this type of requirement are based on n identical and autonomous satellites whose propulsion is based on a system of thrusters distributed over the whole constellation. The type of thruster used ranges from the standard chemical type to ionic thrusters and field electrical effect propulsion (FEEP) thrusters, this latter technique using the application of high voltages to molecules of cesium or indium to generate a very high speed for propelling the vehicle.
It is well known in the space domain that permanent constraints on designing satellites include minimizing the mass, power consumption and overall size of the satellite or satellites, the overall cost of a satellite and its feasibility being a direct function of those three factors. The mass factor is the dominant factor in relation to the impact on the launch vehicle, all the more so in the context of a constellation with n satellites.
To conform to these various constraints, formation flying concepts utilize n identical satellites propelled by thrusters of diverse technologies, while other concepts call on a mixture of nanosatellites and microsatellites to accomplish reduced or simplified missions. However, in all known cases, each satellite is autonomous and must include all of the standard subsystems. On the other hand, a major drawback of using nanosatellites or microsatellites is that they reduce the extent and final benefit of the mission. It must also be emphasized that many projects, such as those that gave rise to the development of formation flying, cannot make do with the reduced and minimalistic satellite concept that nanosatellites constitute.
The present invention therefore aims to adopt a global approach to the formation flying concept that minimizes the associated masses, volumes, powers and costs.
To this end, this fundamentally innovative approach considers the formation in flight as a whole and not as a combination of n identical satellites, whether the latter are nanosatellites or microsatellites.
Against this background, in order to optimize the final system, the invention proposes in particular to simplify and to specialize as much as possible the role of each element of the satellite. In particular, in accordance with the invention, the role of a satellite of this kind can be split into two totally different functions: a remote function, for example concentration of received and/or sent beams, and a beam processing function. Hereinafter, the concentration function is handled by an entity called a “free object”, referring to an object free floating in space and in the vicinity of the body of the satellite. The second (processing) function is handled by the body of the satellite, i.e. the central portion, referred to hereinafter as the “main body” (which has a similar meaning to the term “hub”), this terminology referring to the combination in that body of all the functions of the satellite, in particular its “intelligent” functions, apart from the function of the free object, i.e. concentrating toward the main body beams received from the Earth or some other source and/or concentrating beams emitted by the main body onto the free object, with the Earth or some other destination.
Thus the invention consists in considering the free objects as independent concentrators floating in space with no function other than relaying beams toward the body of the satellite and/or sending beams coming from the satellite toward a predetermined destination. In so doing, the invention minimizes the free object concept, as a result of which the mass, volume and power parameters can be minimized without reducing the range of the chosen mission.